Intelligent Transportation Systems (ITS) relate to systems in which information and communication technologies are applied in the field of road transport, including infrastructure, vehicles and users, and in traffic management and mobility management. One feature of ITS is the Vehicle-Originating Broadcast (VOB). The originating vehicle broadcasts information about its movements and safety-related attributes frequently to make sure that this information is available to other vehicles so that each receiving vehicle can identify potentially hazardous situations arising from the behavior of the transmitting vehicle.
This typically involves transmission of Basic Safety Messages which need to include the following security requirements: authenticity, integrity, authorization and privilege classes, non-repudiation of origin and anti-replay related to having a message signature. ITS security standards as disclosed in ETSI TS 102 687 v 1.1.1 incorporated herein by reference, along with “Status of ITS Security Standards”, Document HTG1-1, US Department of Transportation/European Commission, Version 2012-11-12, in their entirety specify the minimum interval between Basic Safety Messages as 40 ms. Any VOB system that satisfies the standard needs to be able to send a Basic Safety Message every 40 ms. However, as noted above, each Basic Safety Message requires a message signature to satisfy security requirements which means the Basic Safety Message needs to be signed. Given that the minimum message interval is 40 ms, the total time budget available to generate a complete digital signature is 40 ms. However, from an application point of view, it is typically not acceptable to impose a latency of up to 40 ms for generation of a digital signature, especially for Basic Safety Messages. This typically requires that the signature generation latency be below about 10 ms. Note that signature generation (signing the message) needs to be performed in a secure environment such as that offered by a secure element or more precisely by the secure element's software crypto library and the cryptographic coprocessor whereas signature verification does not need to be performed in the secure environment. The secure environment represented by, for example, the crypto library of the cryptographic coprocessor, typically possesses less powerful hardware than the less secure environment hardware.